Unify type of "cpu_idx" across PSCI module.

NOTE for platform integrators:
   API `plat_psci_stat_get_residency()` third argument
   `last_cpu_idx` is changed from "signed int" to the
   "unsigned int" type.

Issue / Trouble points
1. cpu_idx is used as mix of `unsigned int` and `signed int` in code
with typecasting at some places leading to coverity issues.

2. Underlying platform API's return cpu_idx as `unsigned int`
and comparison is performed with platform specific defines
`PLAFORM_xxx` which is not consistent

Misra Rule 10.4:
The value of a complex expression of integer type may only be cast to
a type that is narrower and of the same signedness as the underlying
type of the expression.

Based on above points, cpu_idx is kept as `unsigned int` to match
the API's and low-level functions and platform defines are updated
where ever required

Signed-off-by: Deepika Bhavnani <deepika.bhavnani@arm.com>
Change-Id: Ib26fd16e420c35527204b126b9b91e8babcc3a5c
diff --git a/plat/arm/board/sgm775/include/platform_def.h b/plat/arm/board/sgm775/include/platform_def.h
index 27d1b33..d165ff9 100644
--- a/plat/arm/board/sgm775/include/platform_def.h
+++ b/plat/arm/board/sgm775/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,8 +9,8 @@
 
 #include <sgm_base_platform_def.h>
 
-#define PLAT_MAX_CPUS_PER_CLUSTER	8
-#define PLAT_MAX_PE_PER_CPU		1
+#define PLAT_MAX_CPUS_PER_CLUSTER	U(8)
+#define PLAT_MAX_PE_PER_CPU		U(1)
 
 /*
  * Physical and virtual address space limits for MMU in AARCH64 & AARCH32 modes